机械疲劳损伤的多源激励-光纤光栅分布动态检测的新原理与新方法

Mechanical fatigue damage,which affects seriously the safe operation of the mechanical equipment, has the characteristics of potential, wastage, gradual change and diversity. In view of the complexity of mechanical fatigue damage changes and difficulties of distributed dynamic monitoring, this project proposes a new principle and method of dynamic detection based on ultrasonic and vibration multi-source excitation- fiber grating sensing distributed sensing for mechanical fatigue damage, taking the engine casing and other complex mechanical structures as the object.It performs studies by focusing on the basic scientific problems, such as the coupling mechanism of multi-source excitation signals and the modulation mechanism of mechanical fatigue damage under the excitations, data fusion of distributed fiber Bragg gratings sensing signals, the mapping relationships between mechanical fatigue damage characteristics and the fiber grating sensing signals. According to the study, this project will solve the key problems, such as dynamic detection, characterization and identification of fatigue damage for complex mechanical structure.The main feature and innovation of this project is to create the new principle and method of distributed dynamic detection based on complex mechanical structure fatigue damage, taking advantage of ultrasonic detection and vibration detection, breaking through the limitations of the traditional detection methods for mechanical fatigue damage by the combination of the multi-source excitation and the fiber grating dynamic detection. The research of this project has an important significance of realism and society to further enrich and develop the theories of mechanical fatigue damage detection, to provide a scientific basis for safety monitoring and operation of do mestic machinery and equipment.

机械疲劳损伤具有潜在性、耗损性、渐变性和多样性等特点，严重影响机械装备的可靠安全运行。本项目以航空发动机机匣等复杂机械结构为对象，针对机械疲劳损伤变化复杂、分布动态监测困难的难题，提出超声和振动多源激励-光纤光栅分布传感的机械疲劳损伤动态检测原理和方法的研究，重点围绕多源激励信号的耦合机理及机械疲劳损伤对激励信号的调制机制、光纤光栅分布传感信号的配准融合、机械疲劳损伤特征与光纤光栅分布传感信号的映射关系等基础科学问题展开研究，解决复杂机械结构疲劳损伤动态检测、表征与分析识别等关键技术问题。主要的特色和创新点表现在发挥超声探测和振动测试技术的优势，通过多源激励与光纤光栅分布动态检测的结合，创建面向复杂机械结构疲劳损伤的复合式分布动态检测新原理和新方法。本项目的研究对进一步丰富和发展机械测试理论、方法和技术具有重要的意义，可为机械装备可靠安全运行的监测提供科学依据。

复杂机械装备是国民经济和国防建设的基础性和战略性装备，一旦发生结构损伤，将会给国民经济发展和国防建设带来严重影响和损失。因此，对复杂机械结构进行动态健康监测，明确损伤位置和大小，对保证机械系统安全可靠运行有着十分重要的意义。.本项目围绕机械疲劳损伤发生发展的复杂性和各种现有检测手段的局限性等问题，提出了多源激励-光纤光栅分布传感复合检测思想和方法。重点研究了多源激励信号的耦合机理与机械损伤对激励的调制作用，讨论了不同多源激励模型下（振动-振动激励模型、振动-超声激励模型和超声-超声激励模型）各激励参数对激励之间耦合作用的影响以及机械损伤对激励的调制现象，明确了机械损伤在多源激励-光纤光栅分布传感信号的表征，建立了有效的特征信号分析处理方法。研究了光纤光栅传感特性的影响因素，通过对粘贴工艺的研究，揭示了粘贴型光纤光栅的传感特性与粘胶厚度之间的关系；通过对光纤光栅应变传感方向性的研究，奠定了机械损伤区域化搜索、识别和定位的基础；通过研究不同激励参数对光纤光栅传感灵敏度的影响，建立了多源激励-光纤光栅分布传感的机械损伤测试实验系统，明确了较为合理的激励参数、光纤光栅参数及分布传感的拓扑结构选择原则。在此基础上，针对不同多源激励模型，重点研究了机械损伤的特征信息识别方法和定位算法，明确了机械裂纹等损伤的大致区域，其中一种定位算法为光纤光栅分布传感模式下独有，它利用了光纤光栅应变传感的方向性，突破了传统超声检测定位算法必须依赖超声声速的局限。.这项研究为机械装备在线监测和安全维护提供了新思路和新方法，对进一步丰富和发展机械测试理论、方法和技术，提升机械疲劳损伤的检测能力都具有重要意义。